AB1333 ULTRASOUND FINDINGS IN NORMAL ANKLES – ULTRASOUND-MRI COMPARISON
Authors: L. Enache, C. Popescu, C. Codreanu
Journal: Annals of the Rheumatic Diseases (2022)

Background Although in recent years efforts have been made to standardize the protocols of ultrasound acquisition for each anatomical region, as well as the definitions and quantification of pathological findings, there is still an unanswered question: what should an ankle joint look like in a healthy subject? Objectives The study aims to describe ultrasound changes in the ankles of healthy subjects and to compare the ultrasound method with MRI. Methods The study included healthy volunteering adults, without any ankle symptoms or local pathological medical history. The right ankle was examined clinically, by ultrasound (by the same expert, using a Esaote MyLabTwice with a 12-18 MHz linear probe, with standard definition of imaging findings [1-4]) and by MRI without contrast (by the same expert, using a 1.5 T GE Optima 450 WGEM machine, with standardized definitions of finding [5-7]). Results The study included 25 healthy subjects, with a median age of 54.6 ± 11.8 years, mostly women (84%). Ultrasound identified minimal synovial effusion (SE) in the tibiotalar joint (TTJ) in 20% of subjects (24% on MRI, overall agreement - OA=88%, k=0.65, sensitivity=66.7%, specificity=94.7%), in equal proportions between the anterior and posterior recess (12% on ultrasound and 16% on MRI). One subject had SE in both TTJ’s recesses. Ultrasound minimal SE was also found in the subtalar joint in 36% of subjects (44% on MRI, OA=92%, k=0.83, sensitivity=81.8%, specificity=100%), only in the posterior recess (8% in the anterior recess on MRI, with 2 subjects having SE in both recesses). A minimal amount of SE in tendon sheets, only in the medial ankle compartment (flexor tendons, retro and infra-malleolar segments), was also found and quantified in ultrasound mode B as grade 1 tenosynovitis: 20% in tibialis posterior (48% on MRI, OA=72%, k=0.43, sensitivity=41.7%, specificity=100%, mean MRI thickness of 1.28±0.26mm – grade 1), 16% in flexor digitorum longus (32% on MRI, OA=76%, k=0.36, sensitivity=37.5%, specificity=94.1%, 2.70±2.39mm, of which 24% grade 1 and 8% grade 3) and 20% flexor hallucis longus tendons (32% on MRI, OA=88%, k=0.69, sensitivity=62.5%, specificity=100%, 1.38±0.69mm, of which 28% grade 1 and 4% grade 3). There were no cases of articular or tendon sheath synovial hypertrophy and no cases of intra- or peri-articular power Doppler signals. Conclusion Ultrasound has proven to be an accurate imaging method for ankle examination. Healthy subjects may exhibit minimal ankle intra- and peri-articular SE, especially in the posterior recess, respectively in the medial compartment of the ankle, which may imply that these findings should not be of clinical relevance in the diagnostic evaluation or monitoring of rheumatoid arthritis disease activity. References [1]Wakefield RJ et al. J Rheumatol. 2005;32(12):2485-7. [2]D’Agostino MA et al. RMD Open. 2017;3(1):e000428. [3]Szkudlarek M et al. Arthritis Rheum. 2003;48(4):955-62. [4]Naredo E et al. Ann Rheum Dis. 2013;72(8):1328-34. [5]Ostergaard M et al. J Rheumatol. 2003;30(6):1385-6. [6]Ostergaard M et al. Ann Rheum Dis. 2005;64 Suppl 1:i3-7. [7]Haugen IK et al. Ann Rheum Dis. 2011;70(6):1033-8. Disclosure of Interests None declared